Process of manufacturing pigments



(No Model.) 2 Sheet-s-Sheet 1. F. L. BARTLETT. r,PROGESS 0FMANUFACTURING PIGMENTS.

No. 406,869. Patented July 16, 1889.

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Patented July 16, 1889.

witnesses Inventor N PETERS. Pholvulbognpmr. Wnhmmnn, D. C.

UNITED STATESI PATENT OFFICE.

FRANK L. BARTLETT, OF PORTLAND, MAINE.

PROCESS OF MANUFACTURING PIGMENTS.

SPECIFICATION forming part of Letters Patent No. 406,869, dated July 16,1889.

Original application filed September l5, 1887, Serial No. 249,775.Divided and this application filed March 8, 1839. Serial No. 302,517.(No model.)

To all whom t may concern:

Beit known that I, FRANK I.. BARTLETT, residing at Portland, in thecounty of Cumberland and State of Maine, have invented certain new anduseful Improvements in Process of Manufacturing Pigments 5 and I dohereby declare that the following is a full, clear, and exactdescription of the invention, which will enable others skilled in theart to which it appertainsto make and use the same.

My invention relates to the manufacture of paint-pigments direct fromthe ores of lead, Zinc, sulphur, or antimony, or mixtures of these.Ilitherto such pigments have been made by the following well-knownmethods, namely:

Zinc oxide has been made from the carbonate and oxide ores of zinc bymixing the ore in afinely-pulverized state with equal weights ofanthracite coal, vand blowing' in air in the well-known lVetherillhearths. Sulphide of zinc has also been converted into the oxide by thismethod after first roasting the ore to drive off the sulphur. Certainimpurities i11- terfere with the successful working of this process,only pure high grade ores being adapted to it, and no attempt was madeto save the non-volatile metals-as copper, gold, and silver-when theyhappen ed to be present. The loss was also very large, as from eight totwelve per cent. of the metal was always left in the slag.

Sulphate-of-lead pigment was made by the Lewis-Bartlett process byoxidizing the ore in hearth-furnaces into a crude pigment and thenrefining' it in a blast-furnace into a white pigment. In this processonly pure galena was used, and no attempt was made to save gold erotherprecious metals if present. Some attempt has also been made inordinary blastfurnace smelting to save such fumes as come over fromsmelting ores; but the fumes thus saved were of dark color and tit onlyfor resmelting into the metals.

The class of ores to which my present invention is applied particularlyis known as complex ores. These ores are mixtures of Zinc, copper, lead,silver, gold, antimony, and arsenic, either all together or two or moreof them held in combination with sulphur, and termed sulphurets. Thepresence of zinc in these ores is considered by smelters asobjectionable, since it causes loss of the precious metals in smelting.Moreover, such ores have to be carefully roasted to expel the sulphurbefore they can be smelted by the usual pro cesses. In the presentmethod of smelting there is not only loss of the precious metals whenzinc is present, but the zinc itself is lost in the process.

My process is based upon the following facts or discoveries, believed tobe hitherto unknown, namely: First, when complex sulphuret ores aresmelted in the raw or natural state,without previous roasting, and withsuitable fuel and i'luxing material, in a strong blast of air, thevolatile elements-zinc, lead, and antimony-can be driven off in anatm0sphere of sulphurous oxide-as oxides, sulphates, and oxysulphurets,or mixtures of these-to form Valuable white pigment.,wl1ile the silver,gold, and copper suffer slight loss, and can be saved by drawing themthrough suitable openings in the bottom of the furnace; and, second, iffumes of zinc, lead, or antimony, when in a highly-heated state, arepassed through closed passages externally cooled, the product isinstantly rendered white and increased in body.

The object of my invention is to devise a process by which complex andlow-grade ores may be transformed in a single operation into pure whitemarketable pigment,while the precious metals which may be contained inthe ores are saved with but tritling loss.

In the accompanying drawings I illustrate the apparatus by which myinvention is preferably carried into effect.

In the drawings, Figure l representsa side elevation of the furnace.Fig. 2 is a central longitudinal section through the same. Fig. 3 is aperspective view of a special tile used in the regenerating apparatus.Fig. 4 is a section through oc @c of Fig. Fig. is a section through cca: of Fig. 2. Fig. Gis a section through Y Y of Fig. 2.

A represents a blast-furnace havingwaterjacketed sides and ends.Although I prefer to use a furnace of this description, an ordinarybrick or stone furnace may be used. The furnace is comparativelyshallow, and has a length which is considerably in excess IOO of itswidth, and in its side it has numerous tuyeres or air-blast holes l) b,all pointing sharply downward. At the bottom of the furnace aretap-holes c c". An air-pipe K connects with the tuyercs l), and extendsalong the side of the furnace, which is also provided with feeding doorsor openings a at its top.

Connected with the furnace A and forming part thereof is theregenerating or oxidizing furnace B, the opening or iiue between the twobeing filled by the smoke consumer or regeneratorM,wl1ich is preferablyconstructed of the tiles shown in Fig. 3,1aid in such away that the gasin passing through it follows a zigzag passage and comes in frequentcontact with the surfaces of the tiles. Each of these tiles consists ofa central bar m', at each end of which are offsets or projections m,extending laterally in three directions at right angles to each otherand to the central bar. The tiles can thus be built up to form a mass ofbrick-work traversed by indirect passages, wherein the gas is brought infrequent contact with the surfaces of the tiles.

The furnace B is provided with bridgewalls O2 C2, between which aregrates c c.

Opening underneath the grates c c are various branches j j from theair-supply pipe J. An air-pipe I, situated at the top of the furnace, isprovided with branches I', some of which open'into the space or fluebetween the furnaces B and A, and some enter the bridge-walls C2 of thefurnace B, which are there supplied with perforaticns, by which the airfrom the pipe is discharged into the furnace B.

The regenerating-furnace B connects with an ante-chamber C, from which apassage L leads over the furnace A to the top ot' the cooling-chamber E.The cooling-chamber E consists of a closed chamber having two horizontalflue-sheets c3, one near its top and one near its bottom, theseflue-sheets being connected by vertical tubes e', which open into thespaces above and below said flue-sheets. A partition c2 divides thespace above the upper nue-sheet into two parts, and into one of thesespaces opens the passage L, above dcscribed, and from the other leadsthe pipe G. The pipe K connects with the space surrounding the tubesjustabove the lower Hue-sheet, while a pipe I" enters the same spacenearits top. The pipe F connects with the pressureblower F. The pipe G,which leads from the top of the cooler E, passes to a settling-chamberD, from which the pipe II leads to the bag-room or dust-collectingapparatus. g g are the inlet and outlet water-pipes of the water-jacketof the furnace A. Dampers CZ d control the air-blast in the pipes I I',j j, and K.

In carrying out my process I may make use of any simple ores which arecapable of producing a pigment; but I prefer to use the coinplex orsulphuret ores, for the reason that they are lowgrade ores ofcomparatively small value for smelting purposes, and when worked by myprocess they produce the best pigment. As Will be hereinafter pointedout, the apparatus can be run so as to produce the pure oxide pigmentsor the mixtures of oxides and sulphates, sulphurets, che., before spokenof g but since the latter product is the most valuable and the mostcheaply made, for the reason that it utilizes a large proportion ofsulphur, I prefer to operate it with that end in View, and, in fact,itis for the manufucture of this product that the apparatus is chieiiydesigned.

When sulphuret ores are to be treated, the processV is as Wfollows,namely: The ores, crushed to the size of a pea, are mixed with abouttwentyfive to thirty per cent., by weight, of coke, charcoal, or otherfuel, together with a suitable amount of fluxing material when thenature of the ore requires it. If the zinc or lead ores to be treatedare not sulphurets, or, if they do not contain at least ten per cent. ofsulphur, crude sulphur or sulphuret of iron is added to bring it up tothis proportion. The mixture is charged into the blast-furnace in ashallow layer. (In practice Ido not put in over eighteen inches of ore,&c.) This furnace is supplied with a hot-air blast through. the tuyeresbfrom the pressure -blower F, the current of `air passing through thecooling-chambers E, where it cir-- culates outside the flues e', and isheated by the hot gases which'are passing through these tubes, ashereinafter shown. It is designed to maintain an even temperature in thefurnace by charging the two ends alternately through the doors a a, thusalways maintaining a bright glowing re in one end. The colnbustion ofthe fuel liberates the sulphur, which, igniting. assists combustion, andis converted into sulphurous oxide gas. The non-volatile metals-such asgold, silver, and copper will fuse and settle to the bottom of thefurnace in the formof mattes, and as they accumulate they are drawn oitthrough thc tap-hole e. The earthyimpurities-such as silica,alumina,&c.-unite with the lime and iron and form slag, which is drawnoff through the tap-hole c4, which is slightly higher in elevation thanthe tap-hole e. The zinc, lead, and autimony are reduced and volatilizedand pass off in an atmosphere composed of the other products ofcombustionsuch as sulphurousoxide,carbonic oxide, carbonic-acid gas, andfree nitrogen-as oxides, sulphates, and' oxysulphurets of the metals.These fumes and products of combustion, carrying along with them acertain amount of unconsumed carbon vand raw ores and other impurities,first meet the air-supply which is blown in over the furnace and passthrough the smoke-consumer M, where they come in contact with theincandescent tiles and where such impurities are wholly or partiallyoxidized. In passing through the smoke-consumer M the fumes also becomediffused, and in this state they enter the furnace B and IOO IIO

pass over the regenerating or oxidizing fires, which are kept up oflight coke in one or more of the divisions of the furnace B. These firesare supplied with air from the pipe J, and air is also blown in throughthe perforated pipes I contained in the bridge-walls C2, mixingintimately with the fumes as they pass through the furnace. The effectof the regenerating-lire, the smoke-consumer IWI, and the air upon thefumes is to reduce any portions of raw ore passing over from the furnaceA and to regenerate the heat, which must be kept up to a high degree toinsure the success of the process.

Sufficient air is admitted to decompose any unburned raw ore that may bedriven over from the furnace A,as described. No excess of air is allowedto enter, since it would have a tendency to completely oxidize themetals, forming oxides, which are not so desirable as a product as theoxysulphurets. The dampers (l enable the operator to completely controlthe air-blast, so that the fumes can be run in a full atmosphere ofsulphurous oxide or in a mixture of that and atmospheric air, asdesired. It is desirable to keep the gas in which the fumes aresuspended strongly sulphurous, so that the sulphates and sulphurets willform as freely as possible. The now partially-refined fumes pass overinto the ante-chamber C, where the heavy impurities are deposited,thence through the pipe L to the cooler E, where they pass downwardthrough the ilues c', which are cooled by the cold air from the blowerpassing around them to the bottom of the cooler and thence upl ward andout through the pipe G.

I have found that the highly-heated fumes passing through contractedpassages which are externally cooled are suddenly rendered white andfreed from the dark-colored impurities which cling to them. This effectI understand to be due partly to the mechanical action of the gaspassing through the small tubes or contracted passages andthe agitationincident thereto, whereby the Hakes of pigment into which it is firstformed are broken up and the impurities released, and partly to thesudden change of temperature, which contributes to this result. Thisexplanation may or may not be correct, and I do not base my claim on it,but on the fact as pointed out. It will be observed that, since the hotgas passes inside the tubes and the cold air from the pressure-blowerpasses on the outside of such tubes, the gas is cooled at the same timethe air is heated, both of which results are desirable. The fumes afterleaving the cooler E pass through the pipe G to the settling-chamber D,where the speed of the current is so reduced that all the remainingimpurities settle, the refined pigment being drawn by an exhaustfan orother suitable means to a bag-room or dust-collector.

Itis evident that the apparatus herein described maybe varied as to itsdetails to a very considerable extent Without departing from the spiritof my invention.

I do not wish to confine myself to the exact regenerating apparatus hereshown, as any suitable means can be used for this purpose. After thefurnaces are Well started and the brick-work thoroughly heated through,I find that it is not always necessary to keep the fires in theregenerating-furnace in operation, the incandescent tiles and theair-blast being sufficient to accomplish the desired result without theaid of the coke fires.

In another application (Serial No. 240,775, filed September 15,1887)relating' to the same subject-matter I claim some of the features hereindescribed and shown.

I claiml. The herein-described process of manufacturing pigment, whichconsists in mixing the ores of lead, zinc, or antimony with carbon,subjecting the mixture to an air-blast'in a suitable furnace, thensuccessively supplying air to the fumes thus produced, bringing theminto contact with incandescent fire-clay or other refractory material,subjecting them to the action of an oxidizing-flame, then suddenlycooling them, substantially as shown.

2. The herein-described process of manufacturing pigment, which consistsof mixing the ores of lead, antimony, or zinc with carbon, subjectingthe mixture to an air-blast in a suitable furnace, then successivelysupplying air to the fumes thus produced, bringing them into contactwith incandescent fire-clay or other refractory material, subjectingthem to the action of an oxidizing iiame, and iinallyv collecting them,substantially as shown.

3. The herein-described process of manufacturing pigment, which consistsin mixing the ores of lead, zinc, or antimony with carbon, subjectingthe mixture to an air-blast in a suitable furnace, then successivelysupplying air to the fumes thus produced, bringing them into contactwith incandescent fire-clay or other refractory material, subjectingthem to the action of an oxidizing-flame, Withdrawing saidoxidiZing-flanie after the apparatus becomes heated through, thensuddenly cooling them when in a highly-heated state, and finallycollectingthem,substantially as'shown.

In testimony that I claim the foregoing as my own I have affixed mysignature in presence of two witnesses.

FRANK L. BARTLETT.

Witnesses:

S. XV. BATES, C. SEVERANCE.

IIO

